Activation of satellite cells and expansion of the muscle progenitor cell (MPC) population are essential to generate a sufficient number of cells to repair damaged skeletal muscle. Proliferating MPCs have high energetic and biosynthetic material requirements, and the ability to utilize oxidative phosphorylation (OXPHOS) and/or glycolysis may affect expansion capacity of MPCs. In the present study, we investigated the effect of donor age and sex on human (h)MPC expansion capacity and metabolic fuel preference. hMPCs from young and old male and female donors were grown for 408 h (17 days). Percent confluence, live nuclei count, and dead cell count were measured every 24 h. Metabolic phenotype was assessed by glucose uptake, expression of genes related to glycolysis and OXPHOS, and the Seahorse XF24 Phenotype Test Kit during the exponential phase of growth. hMPCs from old male donors had impaired expansion capacity secondary to heightened cell death early in expansion compared with hMPCs from young male donors, an effect not observed in female hMPCs. Age-related differences in metabolism were also sex dependent; markers of OXPHOS were altered in old (vs. young) male hMPCs, whereas markers of metabolism were largely unaffected by age in female hMPCs. For the first time, we identify sex-specific differences in cell death and OXPHOS that contribute to impaired expansion capacity of hMPC cell populations with age.
Keywords: cell proliferation; metabolism; muscle progenitor cells; sex differences.